Extensive intra-hospital spread of a methicillin-resistant staphylococcal clone

Int J Infect Dis. Jul-Sep 1998;3(1):26-31. doi: 10.1016/s1201-9712(98)90091-1.


Objective: Infection by antibiotic-resistant bacteria can pose serious complications to the therapy of cancer patients. The authors introduced DNA fingerprinting techniques for tracking methicillin-resistant Staphylococcus aureus (MRSA) clones recovered at a central cancer hospital of Lisbon (Instituto Português de Oncologia) with the purpose of making an inventory of the MRSA clones endemic during 1995, and compared them with the outbreak-related clones of 1993.

Design: A small group (6 strains) of epidemiologically related MRSA isolated during a suspected outbreak in 1993 and all consecutive single-patient isolates of MRSA (34 strains) recovered between January and November of 1995 from infected patients and health care personnel were characterized using DNA probes and pulsed-field gel electrophoresis.

Results: The six 1993 strains and more than half of all 1995 isolates, including those recovered from the health care personnel, showed DNA fingerprints characteristic of the "Iberian MRSA," a multiresistant clone widespread in Portuguese and Spanish hospitals. Four patients were infected by another MRSA clone previously seen only in hospitals in Brazil.

Conclusion: The epidemic Iberian clone was among the index cases involved with the MRSA outbreak in 1993, and this was found to be endemic in a follow-up survey conducted in 1995, colonizing health care personnel and spreading to most hospital wards. A few isolates of another epidemic clone, the Brazilian MRSA, also were detected among 1995 isolates. A better understanding of the mechanism(s) of epidemicity of these rapidly spreading clones is urgently needed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Blotting, Southern
  • Cross Infection / epidemiology
  • Cross Infection / microbiology*
  • DNA, Bacterial / analysis
  • Disease Outbreaks
  • Electrophoresis, Gel, Pulsed-Field
  • Female
  • Humans
  • Longitudinal Studies
  • Male
  • Methicillin Resistance*
  • Middle Aged
  • Molecular Epidemiology
  • Staphylococcal Infections / epidemiology
  • Staphylococcal Infections / microbiology*
  • Staphylococcus / classification
  • Staphylococcus / drug effects*
  • Staphylococcus / genetics
  • Staphylococcus / isolation & purification


  • DNA, Bacterial